Installing Skylights: A Roofer's Guide to Installation Best Practices

Overview

Published in the May/June 2024 issue of Roofing magazine (pages 42 to 45) and online on 9 June 2024, this four-page "Details" column is written by Glenn Ferris of the Fenestration and Glazing Industry Alliance (FGIA). It addresses the roofing contractor's recurring fear that a skylight is a leak waiting to happen, and answers it by walking through the industry's own installation guidance, AAMA 1607-14, for the two commercial roof types contractors meet most often: flat single-ply membranes and steeper standing-seam metal.

Key Findings

• Leaks blamed on skylights are usually installation failures, not product failures. Ferris's line that "a great product is only as good as its installation" sums up the argument, and he adds that misused sealant, applied to dam water rather than manage it, is a frequent culprit.
• Demand is rising: the global skylight market is growing year over year on daylighting, sustainability and energy-reduction drivers in commercial, institutional and industrial work. He points readers to AAMA SKY-3-20, FGIA's design guide for unit skylights, tubular daylighting devices and sloped glazing.
• Test early. He recommends water-resistance testing to AAMA 501.2 and AAMA 503 whenever skylights sit above critical areas, done as soon as the unit is in and before drywall or interior finishes hide the evidence.
• Low-slope roofs (AAMA 1607 section 6.18): the membrane around a deck-mounted skylight typically goes on after the unit, so rafters cut for the opening may need temporary support and adjacent members reinforcement. Membrane is run up onto the skylight frame and trimmed, a separate counter-flashing membrane laps over it, and weep holes must never be blocked.
• Steep-slope roofs (section 6.10): curb-mounted units on narrow-profile standing seam should have metal panels stopping about 1 inch below the curb's lower edge, top and bottom flashing collars, side panels acting as side flashing, two beads of sealant between sill flange and roof panel, and head (saddle) flashing overlapping the panels, with the skylight frame fastened down on top of the wood curb.
• Safety is treated as part of the installation, not a separate topic. Where glazing is not proven fall-resistant, AAMA 1607 recommends railings, security grids or safety screens, distinct from insect or glass-retention screens, with NIOSH cited as a further reference.

Why It Matters for Daylighting

Most of the resistance a facility owner meets when proposing prismatic skylights over a warehouse or plant floor comes from the roofing side, and it is almost always about leaks. This article is a useful piece to hand a skeptical roofer because it comes from the roofing trade's own magazine and from the fenestration industry's standards body rather than from a skylight vendor. Its specific details, especially the weep-hole warning and the insistence on water testing before ceilings close up, match the failure modes that show up in warranty disputes. The fall-protection paragraph reinforces a point made elsewhere in this library: OSHA-rated screens or fall-rated glazing should be specified with the skylight, not added later.

About the Source

Roofing magazine (RoofingMagazine.com) is a U.S. trade publication for commercial and residential roofing contractors. Author Glenn Ferris has worked in the fenestration industry since 1992 and joined FGIA in 2018, where he serves as liaison to its councils and technical committees; FGIA's Skylight/Sloped Glazing Council has written skylight performance and installation standards for more than 30 years. The library copy is a four-page PageTurnPro printout of the print issue, and the full article is available on the publisher's site.